This invention is related in general to networks and more specifically to systems and methods for manipulating traffic in networks, such as wireless networks, to improve network performance.
Systems and methods for improving network performance and ensuring QOS in wireless networks are employed in various demanding applications, including cellular networks and Wireless Local Area Networks (WLANs). Such applications often demand systems for manipulating traffic that can ensure communications quality and QOS for high-priority communications.
Systems for ensuring QOS are particularly important in Voice-Over Internet Protocol (VOIP) and multimedia-conferencing applications employing WLANs, where signal degradation, network-roaming events, and faulty network Access Points (APs) may unacceptably degrade communications quality.
An exemplary WLAN includes mobile clients, such as laptops employing wireless network cards, that communicate with a network AP. An AP typically includes a transceiver for communicating with the wireless network cards by converting between wired and wireless signals. The AP often acts as a switch or router that facilitates connecting the clients into a broader network and may further facilitate connecting the clients to outside networks, such as the Internet.
A WLAN often includes a central controller that communicates with plural APs. Each AP is associated with a particular coverage area based on the range of the AP transceiver and the range of client transceivers that are communicating the AP.
A client device that traverses several coverage areas within a given WLAN is the to roam between the APs. When a client roams, the client connection to the network is handed off between APs as needed to maintain the client connectivity.
The central WLAN controller may facilitate handoff between APs and manage WLAN traffic. The controller may separate data and control traffic, and send control traffic to a processor and data traffic to a traffic-forwarding device.
Conventionally, a WLAN controller may prioritize data traffic according to predetermined Access Categories (ACs) to facilitate QOS guarantees in accordance with Wireless Multimedia Extensions (WME) techniques. WME, also known as Wireless-Fidelity (Wi-Fi) Multimedia (WMM), is a Wi-Fi Alliance interpretability certification based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11e draft standard. WME provides basic QOS features to IEE 802.11 (Wi-Fi) networks. Unfortunately, WME methodologies often do not provide adequate QOS guarantees, especially in environments with plural roaming clients.
Furthermore, existing WLAN controllers often lack sufficient mechanisms to prevent one type of control traffic from overrunning another. Consequently, a faulty AP or an AP that is infected with a virus or worm may generate control messages that can overwhelm a central controller. An overwhelmed controller may compromise client-roaming, authentication, and/or other behaviors that require control signaling. Furthermore, an overwhelmed controller may have reduced ability to manage radio resources, which may degrade overall network QOS. Accordingly, the WLAN may drop data packets or delay connections when clients roam between APs of a WLAN that receives excess roam requests. Consequently, existing WLANs are often undesirably susceptible to dropped Voice-Over Internet Protocol (VOIP) phone calls, poor audio and video quality, and so on.